Coatings, primers and inks used in packaging and certain converting purposes may need resistance to heat or steam. Such resistance is difficult to achieve based on the components in the composition, the printing process, the substrate used in the packaging and the use of the packaging itself. One such printing process is flexographic printing.
Flexographic printing is an evolving process. Through the years, advances in press components have enabled printers to achieve higher levels of quality and visual impact. One of the most notable recent developments is the escalating use of EC inks, notably ultra violet (“UV”) inks. Offering significant advantages over water and solvent based inks, UV inks are experiencing explosive growth in the flexographic industry.
As industry demands for visual impact increase, printers seek to add color density while preserving or even enhancing image quality. It is the ability of UV inks to positively impact on color density and image quality, while facilitating improvements in printing efficiency that begins to explain its rising popularity. The other and most significant reason for UV's growth is concern over environmental issues.
All types of inks may have many ingredients, but fundamentally an ink has a component which provides color (pigment, dye or colorant) and a liquid base which provides a means of transportation from the ink fountain to the substrate. Other components and additives are included in the ink formulation to control the ink distribution process, fix the pigment onto the substrate, and enhance specific characteristics of the printed image.
When printing with traditional water and solvent-based inks, dryers apply heat to the web. The ink dries through an evaporative process that removes about 35-40% of the delivered ink volume. In other words, you have to deliver 40% more volume to the substrate with water or solvent ink in order to achieve the desired color density.
Solvent-based inks have been popular for many years and provide excellent results on nonabsorbent web surfaces such as poly films. In an era of growing environmental awareness and reducing tolerance for environmental hazards, waste disposal issues are becoming a driving force in the choices manufacturers and printers make. Environmental Protecting Agency (EPA) regulations make use and disposal of solvent materials a cumbersome and expensive process.
This has driven printers to water based inks wherever applicable. Water-based inks have tended to be more difficult to work with on foils, plastics and other difficult substrates, however, and can be very unforgiving.
Cationic inks have been used on such substrates, but their cost is high and the use of cationic inks may not be economical for all printers.
A need exists for a, EC ink, coating and primer composition that can be used on foils, plastics and other difficult substrate applications. Further, a need exists for such inks to be resistant to heat and water, while still maintaining gloss and color strength. A further need exists for such an ink to maintain adhesion and scratch resistance.
These and other needs are met by the present invention.